The present invention relates to an alkaline protease useful as an enzyme incorporated in a detergent; a gene encoding the same; a microorganism producing the same; and a detergent composition containing the same.
Protease has been widely used in a variety of detergents, such as laundry detergents; cosmetic compositions; bath additives; food-modifying agents; and pharmaceuticals such as digestive aids and antiphlogistics.
Of these, proteases used in detergents are produced in largest amounts on an industrial scale and thus account for a significant part of commercial supply. Examples of such proteases include Alcalase, Savinase (product of Novo Nordisk), Maxacal (product of Genencor), Blap (Product of Henkel), and Protease K (KAP, product of Kao Corporation).
Meanwhile, attempts have been made to improve the performance of enzymes used in detergents. For example, Japanese Patent Application Laid-Open (kokai) No. 6-70765 discloses an enzyme having high stability to heat and a surfactant. Japanese Patent Application Laid-Open (kokai) No. 9-121855 discloses an enzyme which acts on insoluble proteins such as keratin and has a high specific activity. Japanese Patent Application Laid-Open (kokai) Nos. 5-211868 and 9-121856 disclose an enzyme having excellent activity in a low temperature range. European Patent No. 0130756 discloses a method for enhancing stability of an enzyme to an oxidizing agent.
In many cases, soils on laundry comprise a plurality of components such as lipids and solid particles other than protein. Therefore, there is demand for a detergent having excellent detergency to such complex soils. In order to meet the demand, generally a plurality of enzymes and surfactants have been incorporated into a detergent.
However, even though a plurality of enzymes are incorporated, their effects cannot be fully exerted if, in the presence of complex soils, the enzymes are unstable and do not exhibit constant and sufficient activity. Conventional enzymes are unsatisfactory in this point.
In view of the foregoing, the present inventors have discovered an alkaline protease which has a constant casein-degrading activity even in the presence of a fatty acid at a high concentration and exhibits excellent detergency even under complex soil conditions; e.g., soils containing protein and sebum.
Accordingly, in one aspect of the present invention, there is provided an alkaline protease which has the following physicochemical properties:
(i) Acting pH range
acting over a wide pH range of 4-13 and exhibiting, at a pH of 6-12, 80% or more the activity at the optimum pH;
(ii) Stable pH range
being stable over a pH range of 6-11 when treated at 40xc2x0 C. for 30 minutes;
(iii) Isoelectric point
having an isoelectric point of approximately 8.9-9.1; and
(iv) Effect of a fatty acid
casein-degrading activity not being inhibited by oleic acid.
In another aspect of the present invention, there is provided a gene encoding the above-described alkaline protease.
In still another aspect of the present invention, there is provided a microorganism producing the above-described alkaline protease.
In yet another aspect of the present invention, there is provided a detergent composition containing the above-described alkaline protease.